1. Field of the Invention
The present general inventive concept relates to an electrophotographic image forming apparatus, and more particularly, to an electrophotographic image forming apparatus including a fusing apparatus fusing an image on a printing medium.
2. Description of the Related Art
In general, an electrophotographic image forming apparatus forms an image by forming an electrostatic latent image using an exposing unit such as a laser scanning unit that receives a digital image signal, developing the latent image into a toner image using a developing agent such as toner, transferring the toner image to a printing medium, and then fusing the toner image on the printing medium by applying heat and pressure. Accordingly, the electrophotographic image forming apparatus includes a fusing apparatus that applies heat and pressure to the toner image to fuse the toner image on the printing medium.
The fusing apparatus includes a heating roller generating heat and a pressurizing roller that is disposed to face a fusing roller to press the printing medium to which the toner image is transferred toward the heating roller. Various types of fusing rollers operating according to the way heat is generated have been developed.
FIG. 1 is a longitudinal cross-sectional view illustrating a conventional fusing apparatus.
Referring to FIG. 1, the fusing apparatus includes a heating roller 10 and a pressurizing roller 20.
The heating roller 10 includes a tubular metal core pipe 12, an elastic rubber layer or a release layer 13 formed on an outer circumference of the metal core pipe 12, and a halogen lamp 11 which is placed inside the metal core pipe 12 and generates heat. The elastic rubber layer is elastically deformed when contacting the pressurizing roller 20, thereby a nip being easily formed therebetween. The release layer 13 is coated with Teflon™. The heat generated from the halogen lamp 11 is transferred to the metal core pipe 12 by radiation, and is further transferred to the outer circumference of the metal core pipe 12 by conduction.
The pressurizing roller 20 faces and contacts the heating roller 10, and is pressed toward the heating roller 10 by an elastic unit (not illustrated), thereby pressing a printing medium that passes between the pressurizing roller 20 and the heating roller 10. The pressurizing roller 20 includes a tubular metal core pipe 21 and a release layer 22 formed on the outer circumference of the metal core pipe 21.
The fusing apparatus having the above-described structure has a large thermal capacity, and thus the fusing apparatus takes a considerably long warm-up time to reach the fusing temperature when power is supplied for printing. Thus, the first print out time (FPOT) is long.